Resin containers, representative examples of which are oriented polypropylene (OPP) bottles and polyethylene naphthalate (PET) bottles, are used for a variety of purposes, from beverages to food products and cosmetics. Such containers are generally formed by heating resin preform, which has been formed into a bottomed cylindrical shape by injection molding or the like, to a temperature at which a stretching effect can be achieved, and then in this state, feeding pressurized air into the preform while using a stretching rod to blow mold the preform into a predetermined shape (for example, see JP 2003-251685 A).
One known blow molding device that performs such two-axis stretching blow molding is provided with a batch-type mold that includes a plurality of cavities, and using this mold, a plurality of preforms can be blow molded simultaneously. In this case, the preforms are heated by a heating furnace while the preforms are arranged in series and transferred, and the preforms that are sent out from the heating furnace in sequence one at a time are arranged in the cavities of the batch-type mold by a transfer machine. After the preforms are arranged, pressurized air is fed to the preforms in the cavities from a nozzle unit for feeding pressurized air to blow mold the preforms.